Software Update for Q5 always says "interrupted"

My Q5 OS is 10.1.0.2342 and each time I download 10.2.1.2977 which is 1.1 Gb, it installs up to about 89% then says "software update interrupted". I am very much fed up with this. I've ended up deleting almost all my apps just to create space for this update.
Please help me